Energy delivery device and methods of use

ABSTRACT

An energy delivery system for delivering electrical energy to tissue, includes an elongate catheter member defining a longitudinal axis and dimensioned for passage within a body vessel and an expandable treatment member mounted to the catheter member. The treatment member includes an inflatable element adapted to transition between an initial condition and an at least partially expanded condition upon introduction of an anesthetic solution within the inflatable element, an electrode for delivering electrical energy to at least the nerve tissue associated with the body vessel to cause at least partial denervation thereof and at least one aperture dimensioned to permit passage of the anesthetic solution from the inflatable element to contact the body vessel whereby the solution at least enters the body vessel to at least partially anesthetize the nerve tissue therewithin. The electrode may be mounted to at least the inflatable element of the treatment member and may be generally helical.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of, and priority to, U.S.Provisional Application Ser. No. 61/624,206 filed on Apr. 13, 2012, theentire contents of which are incorporated herein by reference. Thisapplication is also related to and incorporates by reference herein thecomplete disclosures of the following patent applications: U.S.Provisional Pat. App. No. 61/113,228, filed Dec. 11, 2008; U.S.Provisional Pat. App. No. 61/160,204, filed Mar. 13, 2009; U.S.Provisional Pat. App. No. 61/179,654, filed May 19, 2009; U.S. Pat. App.Pub. No. 2010/0204560, filed Nov. 11, 2009; U.S. Provisional Pat. App.No. 61/334,154, filed May 12, 2010; U.S. Pat. App. No. 13/106,658, filedMay 12, 2011; U.S. Provisional Application Ser. No. 61/541,756, filed onSep. 30, 2011; U.S. Provisional Application Ser. No. 61/593,147, filedon Jan. 31, 2012; and PCT Application No. PCT/US12/57967, filed on Sep.28, 2012.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

TECHNICAL FIELD

The present disclosure relates generally to medical devices and methodsand more particularly to devices and methods for applying radiofrequencyenergy to tissue.

BACKGROUND

Some medical treatment procedures involve the disruption of a region oftissue. For example, medical treatment procedures include the deliveryof energy to disrupt a region of tissue. Radiofrequency (“RF”) energydevices are an example of devices that can be used to perform suchmedical treatments.

Some RF energy devices have a single RF energy element or a plurality ofdiscrete RF energy elements that have to be repeatedly moved within thesubject in order to apply sufficient RF energy to the entire region ofthe tissue. Such RF energy devices may need to be moved within a patientduring a given procedure, which can increase the complexity, time, andenergy required to perform a given procedure.

SUMMARY

Accordingly, an energy delivery system for delivering electrical energyto tissue, includes an elongate catheter member defining a longitudinalaxis and dimensioned for passage within a body vessel, and an expandabletreatment member mounted to the catheter member. The treatment memberincludes an inflatable element adapted to transition between an initialcondition and an at least partially expanded condition upon introductionof an anesthetic solution within the inflatable element, an electrodefor delivering electrical energy to at least nerve tissue associatedwith the body vessel to cause at least partial denervation thereof andat least one aperture dimensioned to permit passage of the anestheticsolution from the inflatable element to contact the body vessel wherebythe solution enters a wall of the body vessel to at least partiallyanesthetize the nerve tissue there within. The electrode may be mountedto the inflatable element of the treatment member and may be generallyhelical.

In embodiments, the at least one aperture is dimensioned to deliver theanesthetic solution at a pressure sufficient to facilitate passage ofthe anesthetic solution at least within the wall of the body vessel. Atleast one of the inflatable element and the electrode may include aplurality of apertures dimensioned to deliver the anesthetic solution atthe pressure sufficient to cause at least passage of the anestheticsolution within the wall of the body vessel. The apertures may be eachdimensioned to deliver the anesthetic solution at a pressure rangingfrom about 1 atm to about 4 atm and, in embodiments, over a flow rangeof about 1 to about 20 mL/min. Each aperture may define a pore sizeranging from about 0.5 mil to about 10 mil.

In certain embodiments, the catheter member defines a fluid lumen fordelivering the anesthetic solution to the inflatable element of thetreatment member. A source of anesthetic solution may be in fluidcommunication with the fluid lumen of the catheter member and theinflatable element of the treatment member. The system further mayinclude a pump couplable to the fluid lumen of the catheter member. Thepump may be dimensioned to deliver the anesthetic solution from thesource to the fluid lumen of the catheter member at a pressuresufficient to convey the anesthetic lumen through the fluid lumen andout the apertures causing passage of the anesthetic solution at leastwithin the wall of the body vessel. A sensor may be in fluidcommunication with at least the fluid lumen of the catheter member. Thesensor may be a pressure sensor or transducer adapted to sense pressurecorresponding to pressure within the inflatable element. In thealternative, the sensor may be a flow rate sensor adapted to detect flowrate associated with passage of the anesthetic solution through thefluid lumen.

In embodiments, the system includes a controller for controllingoperation of the pump. The controller may include logic responsive to aparameter detected by the sensor to vary operation of the pump.

In some embodiments, the system includes a source of irrigation fluid influid communication with the inflatable element of the treatment memberfor passage through the apertures for, e.g., cooling the electrodeand/or the tissue. The system may further include a valve in fluidcommunication with the source of anesthetic solution and the source ofirrigation fluid. The valve may be actuable between an anesthetic modeto permit the delivery of the anesthetic solution to the fluid lumen ofthe catheter member and an irrigation mode to permit the delivery of theirrigation fluid to the fluid lumen of the catheter member.

In certain embodiments, the at least one aperture of the treatmentmember is dimensioned to permit passage of the anesthetic solution at arelatively pressure whereby the anesthetic solution slowly diffuses atleast within the body vessel and migrates to the nerve tissue associatedwith the body vessel. In instances, the inflatable element of thetreatment member is dimensioned to establish a reservoir between theinflatable element and a wall of the body vessel when in the at leastpartially expanded condition thereof. The reservoir receives theanesthetic solution for diffusion through the wall of the body vessel.

The treatment member may include at least one occluding element. The atleast one occluding element may define a dimension greater than acorresponding dimension of the inflatable element when the at least oneinflatable element is in an at least partially expanded conditionthereof. The at least one occluding element may be dimensioned to atleast partially occlude the body vessel to at least partially enclosethe reservoir.

In some embodiments, the inflatable element is a balloon member. Theballoon member includes first and second axially spaced occludingsegments and a central segment between the first and second occludingsegments. Each of the first and second occluding segments has atransverse dimension greater thas a corresponding transverse dimensionof the central segment when the balloon member is in a first inflatedcondition, and dimensioned to substantially occlude the body vessel toenclose the reservoir. The balloon member may be adapted to transitionbetween the first inflated condition and a second inflated conditionwhere the central segment defines a greater transverse dimension toposition the electrode in opposition to the body vessel to deliverelectrical energy to the nerve tissue associated with and/or surroundingthe body vessel. The catheter member may define a fluid lumen fordelivering the anesthetic solution to the balloon member.

In other embodiments, the catheter member includes first and secondoccluding elements mounted adjacent opposed ends of the inflationelement. The first and second occluding elements may be adapted toexpand to occlude the body vessel and enclose the reservoir establishedbetween the inflatable element and the wall of the body vessel. Thefirst and second occluding elements may be adapted for expansionindependent of expansion of the inflatable element. The first and secondoccluding elements may be first and second occluding balloon members andthe inflation element may be a treatment balloon member having theelectrode mounted thereto. The catheter member may define a second fluidlumen for delivering fluid to the first and second occluding balloonmembers. As an alternative, the first and second occluding balloonmembers may be inflatable independent of each other.

In some embodiments, the treatment member includes a first balloonmember and a second balloon member coaxially mounted about the firstballoon member. The first and second balloon members are dimensioned toestablish a reservoir between the first and second balloon members whenin the at least partially inflated condition thereof. The reservoirreceives the anesthetic solution and the second balloon member mayinclude the at least one aperture dimensioned to permit passage of theanesthetic solution. The first and second balloon members may beinflatable independent of each other. The elongate member may define asecond lumen for supplying fluids to the first balloon member to inflatethe first balloon member.

In accordance with an aspect of the disclosure, a method for treatinghypertension, includes positioning a treatment member including aninflatable segment and an electrode segment within a renal artery;delivering an anesthetic solution into the inflatable segment such thatthe anesthetic solution is released from at least one aperture of thetreatment member to contact a wall of the renal artery whereby theanesthetic solution enters the wall of the renal artery and migrates torenal nerve tissue associated with the renal artery; and emitting RFenergy from the electrode segment to disrupt renal nerve transmission totreat hypertension.

In some embodiments, delivering the anesthetic solution includesdirecting the anesthetic solution to target nerve tissue for alleviatingpain during renal denervation. The targeted nerve tissue may includenerve tissue in the intima, media, adventitia, and/or surrounding tissueof a renal artery. The delivery of the anesthetic solution is at apressure sufficient to enter and/or pass through the wall of the renalartery and contact the desired renal nerve tissue, and may furtherinclude directing the anesthetic solution through a plurality ofapertures in the treatment member at, e.g., a pressure ranging fromabout 1 atm to about 4 atm.

In certain embodiments, delivering the anesthetic solution includespermitting passage of the anesthetic solution at a pressure whereby theanesthetic solution slowly diffuses through the wall of the renal arteryand possibly migrates to the renal nerve tissue surrounding the renalartery. Delivering the anesthetic solution may include distributing theanesthetic solution within a reservoir defined between the inflatablesegment and the wall of the renal artery. In one aspect, the treatmentmember may include occluding segments adjacent each end of the inflationsegment. The occluding segments may be expanded to contact the wall ofthe renal artery to occlude the artery and substantially enclose thereservoir.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B, and 2 illustrate a portion of an energy delivery devicecomprising a helical electrode on an expandable element according to anembodiment of the present disclosure;

FIGS. 3A and 3B show a portion of an elongate device according to anembodiment of the present disclosure;

FIG. 4 shows a portion of an energy delivery device comprising atemperature sensor according to an embodiment of the present disclosure;

FIG. 5 illustrates a portion of an energy delivery device whereinportions of a helical electrode are covered with an insulation materialaccording to an embodiment of the present disclosure;

FIG. 6 illustrates an system for delivering energy to tissue accordingto an embodiment of the present disclosure;

FIG. 7 illustrates a cross section of an energy delivery device with ahelical electrode in use within a renal artery according to anembodiment of the present disclosure;

FIGS. 8 and 9 illustrate a portion of an energy delivery device whereinenergy is delivered to renal nerves through conductive fluid to thetissue according to an embodiment of the present disclosure;

FIG. 10 is a photograph showing tissue ablation in a general helicalpattern caused by an energy delivery device with a helical electrodeaccording to an embodiment of the present disclosure;

FIGS. 11A-11H illustrate a method of manufacturing an energy deliverydevice with a helical electrode on an expandable element according to anembodiment of the present disclosure;

FIG. 12 represents an embodiment of a system similar to that of FIG. 6represented by the resistances of the various elements according to anembodiment of the present disclosure;

FIG. 13 illustrates an alternative configuration in which a capacitor,inductor, or both may be incorporated in the circuit from FIG. 12;

FIGS. 14 and 15 illustrate an embodiment of a pressure sensor accordingto an embodiment of the present disclosure;

FIG. 16 illustrates a portion of an energy delivery device including ahelical electrode pair on an expandable element according to anotherembodiment of the present disclosure;

FIG. 17 is view of a system including an energy delivery device capableof delivering an anesthetic solution to tissue according to anembodiment of the present disclosure;

FIG. 18 is a cross-sectional view illustrating the expandable treatmentmember of the energy delivery device of FIG. 17 delivering an anestheticsolution through a wall of a renal artery and into the surrounding renalnerve tissue;

FIG. 19 is a view illustrating an expandable treatment member of anenergy delivery device adapted to deliver anesthetic solution throughthe wall of the renal artery to the surrounding renal nerve tissueaccording to an embodiment of the present disclosure;

FIG. 20 is a perspective view of an expandable treatment member of anenergy delivery device adapted to deliver anesthetic solstion accordingto an embodiment of the present disclosure;

FIGS. 21-22 are views illustrating an expandable treatment member of anenergy delivery device for delivering anesthetic aohtrion through thewall of the renal artery to the surrounding renal nerve tissue accordingto an embodiment of the present disclosure;

FIGS. 23-25 are views of an expandable treatment member includingproximal and distal occluding elements and a central inflatable clementfor delivering anesthetic solution according to an embodiment of thepresent disclosure;

FIG. 26 is a view of an expandable treatment member for deliveringanesthetic solution according to an embodiment of the presentdisclosure; and

FIG. 27 is a view of an expandable element including coaxially mountedinflatable elements for delivering anesthetic solution according to anembodiment of the present disclosure.

DETAILED DESCRIPTION

Particular embodiments of the present disclosure are describedhereinbelow with reference to the accompanying drawings; however, thedisclosed embodiments are merely examples of the disclosure and may beembodied in various forms. Like reference numerals may refer to similaror identical elements throughout the description of the figures.

This description may use the phrases “in an embodiment,” “inembodiments,” “in some embodiments,” or “in other embodiments,” whichmay each refer to one or more of the same or different embodiments inaccordance with the present disclosure. For the purposes of thisdescription, a phrase in the form “A/B” means A or B. For the purposesof the description, a phrase in the form “A and/or B” means “(A), (B),or (A and B)”. For the purposes of this description, a phrase in theform “at least one of A, B, or C” means “(A), (B), (C), (A and B), (Aand C), (B and C), or (A, B and C)”.

As used herein, the terms proximal and distal refer to a direction or aposition along a longitudinal axis of a catheter or medical instrument.The term “proximal” refers to the end of the catheter or medicalinstrument closer to the operator, while the term “distal” refers to theend of the catheter or medical instrument closer to the patient. Forexample, a first point is proximal to a second point if it is closer tothe operator end of the catheter or medical instrument than the secondpoint. The measurement term “French”, abbreviated Fr or F, is defined asthree times the diameter of a device as measured in mm. Thus, a 3 mmdiameter catheter is 9 French in diameter. The term “clinician” refersto any medical professional (i.e., doctor, surgeon, nurse, or the like)performing a medical procedure.

One aspect of the disclosure is a RF delivery device that is adapted todeliver RF energy to tissue. FIG. 1A illustrates a side view of a distalregion of RF delivery device 10. Device 10 has proximal region 2,intermediate region 4, and distal region 6. Device 10 includes anelongate portion 12 and expandable portion 14 (shown in an expandedconfiguration) disposed on a distal region of elongate portion 12.Expandable portion 14 includes inflatable element 16 on which conductivematerial 18 is disposed.

FIG. 1B illustrates a perspective view of the portion of the deviceshown in FIG. 1A, with a rectangular section of inflatable element 16removed to illustrate elongate portion 12 disposed inside inflatableelement 16.

FIG. 2 shows a sectional view of the portion of the device shown in FIG.1A. Expandable portion 14 includes a proximal transition section 20,intermediate section 22, and distal transition section 24. Proximaltransition section 20 and distal transition section 24 are shown withconical configurations extending towards elongate portion 12 but are notlimited to this configuration. Intermediate section 22 is substantiallycylindrically-shaped when inflatable element 16 is in the expandedconfiguration shown in FIGS. 1A, 1B, and 2. The proximal end ofinflatable element 16 and the distal end of inflatable element 16 aresecured to catheter 26, which is part of elongate portion 12.

Conductive material 18 is disposed on catheter 26 proximal to theexpandable portion 14, and it is also disposed on the cylindricalsection of inflatable element 16 in a helical pattern forming a helicalelectrode 19 as shown. In proximal region 2 and in proximal section 20of the expandable portion, insulation material 34 is disposed on thelayer of conductive material 18. In the cylindrical intermediate section22 of expandable portion 14, insulation material 34 is not disposed onthe helical electrode, allowing energy to be delivered to tissue throughconductive material 18. In the proximal region 2 of the device, and inproximal section 20 of expandable portion 14, conductive material 18 iscovered with a layer of insulation, and thus energy is not applied totissue in those areas. The conductive material that is not covered bydielectric material on the distal portion of the system is considered anelectrode. The conductive material and the electrode are in thisembodiment the same material.

The conductive material 18 is disposed on substantially the entirecatheter 26 in proximal region 2 of the device. “Substantially theentire,” or “substantially all,” or derivatives thereof as used hereininclude the entire surface of catheter 26, but also includes most of thesurface of the catheter. For example, if a few inches of the proximalend of catheter 26 are not covered with conductive material, conductivematerial is still considered to be disposed on substantially all of thecatheter. The conductive material 18 and insulation material 34 extend360 degrees around the catheter shaft, as opposed to only coveringdiscrete lateral sections of the catheter. Alternatively, in someembodiments the conductor covers only a portion of the lateral surfaceof the catheter shaft. The conductive material and insulation materialmay cover the entirety or only a portion of the proximal transitionsection of the expandable portion. The insulation will typically coverthe entirety of the conductive material in this region. The conductivematerial and insulation material could, however, also be disposed on thedistal section 24 of expandable portion 14.

In some embodiments the helical electrode makes about 0.5 revolutions toabout 1.5 revolutions around the inflatable element. The number ofrevolutions is measured over the length of the helical electrode. Theelectrode may extend from the proximal transition section to the distaltransition section (as shown in FIG. 2), but the electrode may extendover any section of the inflatable element. For example, the proximalend of the electrode may be disposed distal to the proximal transitionsection, and the distal end of the electrode may be proximal to thedistal transition section.

One revolution traverses 360 degrees around the longitudinal axis of theexpandable element. One revolution of the electrode, along an end-viewof inflatable device, forms a circle, although depending on the crosssectional shape of the expandable element, the electrode can form anyvariety of shapes in an end-view. An electrode making 0.5 revolutionstherefore traverses one half of 360 degrees, or 180 degrees. Anelectrode making 0.5 revolutions has distal and proximal ends that areon opposite sides of the balloon. In an end-view of the inflatableelement with a circular cross section, an electrode making 0.5revolutions has a semi-circular, or C, shape.

The proximal end of the electrode can be disposed anywhere on theexpandable element and the distal end of the electrode can be anywhereon the expandable element, as long as the proximal end is proximal tothe distal end. In some embodiments, the proximal end of the electrodeis at the boundary between the proximal transition section and thecylindrical intermediate section of the expandable element, and thedistal end of the electrode is at the boundary between the distaltransition section and the cylindrical intermediate section. In otherembodiments the proximal end of the electrode is disposed distal to theboundary between the proximal intermediate section and the cylindricalintermediate section of the expandable element, and the distal end isproximal to the boundary between the distal transition section and thecentral intermediate section of the expandable element. In these otherembodiments the electrode is considered to extend along a subset of thelength of the central intermediate section of the expandable element. Inthe embodiment shown in FIG. 1B, the electrode makes about 1 revolutionaround the inflatable element. In some embodiments the electrode makesabout 0.5 revolutions around the inflatable element. In some embodimentsthe electrode makes about 0.75 revolutions around the inflatableelement. In some embodiments the electrode makes about 1 revolutionaround the inflatable element. In some embodiments the electrode makesabout 1.25 revolutions around the inflatable element. In someembodiments the electrode makes about 1.5 revolutions around theinflatable element.

The device is adapted to be coupled to an RF generator, which suppliesRF current through the conductive material 18 on catheter 26 andinflatable element 16. In this manner RF current can be delivered to thedesired tissue. Energy is thus applied to tissue in the configuration ofthe conductive material on the intermediate section 22 of the expandableportion 14, which in this embodiment is a helical, or spiral,configuration.

Within the expandable portion, catheter 26 is not covered withconductive material or insulation material. Catheter 26 includes guideelement lumen 36 and inflation lumen 28, also referred to herein asirrigation lumen, extending therethrough. Guide element lumen 36 extendsfrom the proximal end of the device (not shown) to the distal end.Irrigation lumen 28 extends from the proximal end of catheter 26 (notshown) to a location within inflatable element 16. Irrigation port 30 islocated inside inflatable element 16 and is in between proximal anddistal ends of irrigation lumen 28. Irrigation lumen 28 and irrigationport 30 provide for fluid communication between the irrigation lumen andthe interior of inflatable element 16. FIGS. 3A and 3B illustrateadditional views of guide element lumen 36, irrigation lumen 28, andirrigation port 30. In some embodiments catheter 26 ranges in size from2 to 8 French, and in some embodiments is 4 Fr. In some embodiments theguide wire lumen is between 1 and 4 Fr and in some embodiments is 2.5Fr.

Expandable portion 14 includes one or more irrigation apertures 38 toallow irrigation fluid to pass from inside inflatable element 16 tooutside inflatable element 16. The irrigation apertures can be formedonly in the electrode section of expandable portion 14 (see, forexample, FIG. 1A), only in the non-elcotrode section of inflatableportion 14, or in both the electrode section and in the non-electrodesection. The irrigation fluid is adapted to cool the conductive material18 and/or tissue. The apertures allow for fluid to flow out of theballoon, allowing either a continuous or non-continuous supply of fluidfrom a fluid reservoir, through the lumen, and into the balloon. Theirrigation fluid is in some embodiments cooled prior to delivery.

FIG. 4 illustrates a portion of an embodiment of a RF delivery device.Delivery device 110 is similar to the RF delivery device shown in FIGS.1-3. Device 110 includes catheter shaft 126 covered with conductivematerial 118, upon which insulation material 134 is disposed. Insulationmaterial 134 is also disposed on the proximal transition section of theexpandable portion 114, similar to the embodiment shown in FIGS. 1-3.The inflatable element also has conductive material 118 disposed on theinflatable element in the form of a helical electrode. Catheter 126 hasguiding element lumen 136 and irrigation lumen 128 therein. Device 110also includes at least one marker 127 disposed on catheter 126 such thatthe marker is within expandable portion 114 (shown as a balloon). Device110 also includes irrigation port 130 in fluid communication withirrigation lumen 134. Device 110 also includes temperature sensor 129,such as a thermocouple, a resistance temperature detector, or athermistor, that is electrically coupled from the proximal end of thedevice (not shown) through irrigation lumen 128, out of irrigation port130, and is secured at its distal region to catheter 126. Thetemperature sensor could alternatively be disposed on the inner or outersurface of inflatable element 116. In some embodiments marker 127 is aradio opaque marker comprised of Pt, PtIr, or other suitable radioopaque material. In some embodiments the marker may also comprisefeatures viewable under fluoroscopy that allow for the visualization ofthe rotational orientation of the marker, and therefore the expandablesection. This allows the physician to note the location of and/orrealign the expandable element and helical electrode as necessary withinthe renal artery.

The irrigation fluid is adapted to cool the electrode on the inflatableelement. The irrigation fluid cools the RF electrode as it flows withinthe inflatable element and after it passes through the apertures as itflows across the outer surface of the inflatable element. Temperaturesensor 129 is adapted to sense the temperature of the fluid withininflatable element 116. The signal from the temperature sensor may beused in a feedback control mechanism to control the flow of fluid from afluid reservoir (now shown) into the inflatable element. Alternatively,the irrigation fluid may be delivered at a substantially constant rateand the signal from the temperature sensor used as signal toautomatically shut off the RF generator if the sensed fluid temperatureis above a threshold limit, thereby terminating that portion of theprocedure. Such a condition is considered a fault and afteridentification and resolution of a fault, a procedure may be restarted.FIG. 5 illustrates a delivery device in which portions of the helicalconductor have been covered by insulation material 734, forming aplurality of discrete circularly-shaped windows surrounding apertures717 on electrical conductor 718. In this fashion a single conductor canbe used to create a number of discrete burn zones following a helicalpath along and around a vessel wall.

In some embodiments, an anesthetic (such us lidocaine) may be added tothe irrigation fluid, in order to reduce patient discomfort. In somesuch embodiments, it might be desirable to deliver the irrigation fluidand anesthetic at a higher pressure in order to achieve better tissuepassage. The anesthetic may be introduced as a bolus in the initial partof the balloon inflation and electrode irrigation procedure.Alternatively, the balloon may be inflated with an anesthetic solutionprior to RF energy delivery, then deflated to remove the anestheticsolution followed by reinflation with a saline solution to serve as theirrigation for the RF procedure. Delivery of the anesthetic solution maybe preceded by inflation of the balloon (such as, e.g., with a contrastagent in the balloon or with saline in the balloon and contrast agentinjected proximally to the balloon) to confirm positioning. Additionalembodiments of energy delivery devices incorporating systems fordelivery of anesthetic solution will be discussed hereinbelow.

One aspect of the disclosure is a system to delivery RF energy totreatment tissue. FIG. 6 illustrates a system 300 adapted to deliver RFenergy to treatment tissue. System 300 includes RF energy deliverydevice 302, which can comprise any of the RF energy delivery devicesdescribed herein. Delivery device 302 is shown including inflatableelement 316, helical energy delivery element 319, irrigation apertures330, guidewire 310, and elongate member 312. System 300 also includesexternal housing 320, which includes display 322 and controller 324.Housing includes connector 336, which is adapted to connect toinstrument interface cable 314. System 300 also includes fluid reservoir326, which is in fluid communication with delivery device 302 viairrigation line 328. The system also includes fluid pump 331, optionalpressure sensor 332, and optional bubble sensor 334. System 300 alsoincludes a grounding plate or set of grounding plates 340 interfaced tocontroller 324 via connector 346.

An embodiment of pressure sensor 332 from the system in FIG. 6 is shownin FIGS. 14 and 15. Pressure sensor 332 includes a housing, whichcomprises capture portion 335 and a force sensor 333. Capture portion335 is configured to substantially surround irrigation tube 328.Additionally, capture portion 335 captures tubing 328 such that aportion of the wall of irrigation tube 328 is compressed against forcesensor 333. The force experienced by the force sensor is then a functionof the force associated by the compression of the irrigation tube andthe pressure within the irrigation tube. In operation, a measurement ismade under a no flow condition that describes the offset associated withthe compression of the irrigation tube. This offset measurement is madeprior to the initiation of a procedure and may be repeated at thebeginning of each power cycle. This value is then used as an offset forsubsequent measurements made under flow conditions. A force/pressurecalibration per tubing type or per tube is then used to convert theforce signal to a pressure value.

The disclosure includes methods of using any of the RF delivery devicesand systems herein. In some embodiments the devices and/or systems areused to treat hypertension by disrupting the transmission within renalnerves adjacent one or both renal arteries.

The present methods control renal neuromodulation via thermal heatingmechanisms. Many embodiments of such methods and systems may reducerenal sympathetic nerve activity. Thermally-induced neuromodulation maybe achieved by heating structures associated with renal neural activityvia an apparatus positioned proximate to target neural fibers.Thermally-induced neuromodulation can be achieved by applying thermalstress to neural structures through heating for influencing or alteringthese structures. Additionally or alternatively, the thermalneuromodulation can be due to, at least in part, alteration of vascularstructures such as arteries, arterioles, capillaries, or veins thatperfuse the target neural fibers or surrounding tissue.

Thermal heating mechanisms for neuromodulation include both thermalablation and non-ablative thermal alteration or damage (e.g., viasustained heating or resistive heating). Thermal heating mechanisms mayinclude raising the temperature of target neural fibers above a desiredthreshold to achieve non-ablative thermal alteration, or above a highertemperature to achieve ablative thermal alteration. For example, thetarget temperature can be above body temperature (e.g., approximately 37degrees C) but less than about 45 degrees C for non-ablative thermalalteration, or the target temperature can be about 45 degrees C orhigher for the ablative thermal alteration.

The length of exposure to thermal stimuli may be specified to affect anextent or degree of efficacy of the thermal neuromodulation. Forexample, the duration of exposure can be as short as about 5, about 10,about 15, about 20, about 25, or about 30 seconds, or could be longer,such as about 1 minute, or even longer, such as about 2 minutes. Inother embodiments, the exposure can be intermittent or continuous toachieve the desired result.

In some embodiments, thermally-induced renal neuromodulation may beachieved via generation and/or application of thermal energy to thetarget neural fibers, such as through application of a “thermal” energyfield, including, electromagnetic energy, radiofrequency, ultrasound(including high-intensity focused ultrasound), microwave, light energy(including laser, infrared and near-infrared) etc., to the target neuralfibers. For example, thermally-induced renal neuromodulation may beachieved via delivery of a pulsed or continuous thermal energy field tothe target neural fibers. The energy field can be sufficient magnitudeand/or duration to thermally induce the neuromodulation in the targetfibers (e.g., to heat or thermally ablate or necrose the fibers). Asdescribed herein, additional and/or alternative methods and systems canalso be used for thermally-induced renal neuromodulation.

The energy field thermally modulates the activity along neural fibersthat contribute to renal function via heating. In several embodiments,the thermal modulation at least partially denervates the kidneyinnervated by the neural fibers via tearing. This may be achieved, forexample, via thermal ablation or non-ablative alteration of the targetneural fibers.

In some uses in which RF energy is used to ablate the renal nerve, theRF delivery device is first positioned within one or more renal arteriesand RF energy is delivered into renal nerves to disrupt the nervetransmission sufficiently to treat hypertension. The disruption patternwithin the artery preferably extends substantially 360 degrees aroundthe artery. Electrodes that treat tissue falling diametrically in asingle plane normal or oblique to the longitudinal axis of the vesselhave been shown to increase the risk of stenosing a vessel treated withRF energy. Spiral, or helical, patterns as described herein createpatterns of treated tissue for which the projection along thelongitudinal axis is circular and therefore have a high probability oftreating any renal nerve passing along the periphery of the renal arery.The patterns, however, have minimal risk of creating a stenosis.Previous attempts have used a point electrode at a distal end or distalregion of a device. In these attempts, the electrode is disposed in therenal artery followed by RF energy delivery. To disrupt renal nervetissue in a non circumferential pattern using a point electrode, thedevice is first positioned within the renal artery adjacent arterialtissue. RF energy is then delivered to disrupt a region of renal nerve.The device must then be moved axially (distally or proximally) androtated, followed by additional RF delivery. The movement and RFdelivery is repeated in a pattern until the renal nerves have beensufficiently disrupted. The repeated movements are time consuming andincrease the complexity of the overall process for the physician. Duringan emergency situation the physician may lose track of the position andsequence of previous burns thereby jeopardizing the likelihood ofcreating a pattern sufficient to treat the neural tissue or be forced toincrease the number of burns thereby over-treating the patient.

Utilizing a single helical electrode as described herein providesprocedural improvements over previous attempts. By using an electrodewith the configuration of the desired treatment region, the device neednot be moved to disrupt tissue in a desired treatment configuration. Inparticular the device need not be moved axially or rotated to treat anentire renal nerve treatment region. This reduces the overall time ofthe treatment. Additionally, this allows energy to be delivered to adesired treatment region in a variety of patients with much greaterpredictability. Additionally, if markers are used that allow forrotational alignment, the device may be moved and/or removed and thenreplaced and realigned, allowing the procedure to be restarted at alater time.

A method of using an RF delivery device to treat hypertension is shownin FIG. 7, and will be described using the device in FIG. 4 and thesystem shown in FIG. 6. The methods described herein can be carried outby other systems and by other RF delivery devices, such as the RFdevices described herein.

The RF delivery device is positioned in a renal artery using apercutaneous access through a femoral artery. The expandable portion isdelivered into the renal artery in a collapsed configuration (notshown). Once the expandable portion is in position, fluid from fluidreservoir 326 is pumped in an open loop control configuration, underconstant flow, through irrigation line 328 and into inflatable element116 by pump 330. Fluid flow into inflatable element 116 causesinflatable element 116 to expand. Device 110 in FIG. 7 is in adelivered, or expanded, configuration within renal artery 1000. Thetunica intima 1001 is surrounded by the tunica media 1002, which is inturn surrounded by adventitial tissue 1003. Tissue renal nerves 1004 areshown within the adventitial, and some renal nerves not shown will befound within the tunica media.

The fluid continually passes through apertures 138 in the expandableportion as it is replaced with new fluid from fluid reservoir 326. Oncefully expanded, the conductive material 118 on the inflatable elementfully assumes the helical configuration, as shown in FIGS. 4 and 7. RFenergy is then delivered to the helical electrode on the inflatableelement. Control unit 324 controls the parameters of the RF alternatingcurrent being delivered through the conductive material on the catheterand the helical electrode on the inflatable element.

In general, the RF signal characteristics are chosen to apply energy todepths at which the renal nerves are disposed to effectively ablate therenal nerves. In general, the power is selected to ablate a majority ofthe renal nerves adjacent to where the device is positioned within therenal nerve. In some embodiments the tissue is ablated to a depth ofbetween about 3 mm to about 7 mm from the tissue closest to the devicein the renal artery.

The RF signal can have the following characteristics, but these are notintended to be limiting: the frequency is between about 400 KHz to about500 KHz and is a sine wave; the power is between about 30 W to about 80W, the voltage is between about 40v and about 80v; and the signal is anintermittent signal.

Tissue treated by the RF energy via the helical electrode comprised isshown as regions 1005, delineated by a dashed line. As illustrated, aregion of treated tissue 1005 adjacent to the cut away section ofconductor 118 includes nerve 1004. The device is shown being used inmonopolar mode with a return electrode 340 positioned somewhere on thepatient's skin.

Control unit 324 controls the operation of pump 330 and thereforecontrols the flow rate of the fluid from reservoir into the inflatableelement. In some embodiments the pump is continuously pumping atconstant flow rate such that the flow is continuous from the reservoir,as is illustrated in FIG. 7. In some embodiments the pump is operated inan open loop constant flow configuration where pump rate is not adjustedas a function of any control parameter other than an over-pressurecondition sensed by pressure sensor 332, in which case RF power deliveryis terminated, the pump is turned off, and an over-pressure conditionreported to the operator. The pump is typically operated for a period oftime which encompasses the delivery of the RF energy and turned offshortly after the conclusion of the procedure or if the pressure sensorsenses an undesirable condition, discussed herein.

The irrigation fluid is delivered from the pump through irrigation line328 to irrigation lumen 128 to irrigation port 130 into the inflatableelement 116, and then out of the inflatable element through irrigationapertures 138. The pressure measured at the pressure sensor is driven byflow rate and the series sum of the fluid resistance of all of theelements in the fluid path. The choice of fluid flow rate is driven bythe required cooling rate and limited by the amount of irrigant fluidthat can be tolerated by the patient which is delivered during the sumof treatments cycles. The system is designed such that at the desiredfluid flow there is a defined operating pressure within the inflatableelement. An optimal inflatable element inflation pressure is a pressurethat is sufficient to completely inflate the inflatable element suchthat the RF electrode engages the treatment tissue. The operatingpressure within the inflatable element will be driven by the fluid flow,the number of apertures, and their cross sections. The distribution,number, and cross section of the irrigation apertures will be driven bythe flow rate, the configuration of the electrode, the intendedoperating pressure, and the maximum desired exit velocity for theirrigation fluid. If the number of apertures is too small and thedistribution too sparse some areas of the surface will not receiveappropriate irrigation and thereby be subject to overheating andpossible charring of tissue. For a set of circular apertures and a givenflow rate, the mean exit velocity for the irrigation fluid will drop asthe number of apertures is increased while decreasing the crosssectional area of each aperture such that the fluid resistance of thesum of apertures is appropriate to maintain the desired inflationpressure. Minimizing the irrigation fluid exit velocity minimizes orprecludes the possibility that lesions will be eroded through thetreatment tissue.

A set of operating conditions and design parameters is now provided, andis not meant to be limiting. An inflation pressure between about 0.5 atmand less than about 4 atm used with a noncompliant inflatable element ofapproximately 0.75 mil (˜19 um) thick ensures tissue engagement in arenal artery. In some particular embodiments the inflation pressure isabout 2 atm +/−0.5 atm. The irrigation fluid delivery rate is betweenabout 1 mL/min and about 20 ml/min. In some particular embodiments thedelivery rate is about 10 mL/min +/−2 mL/min. The expandable portionincludes eight irrigation apertures about 2.6 mil (0.0026 inches) indiameter distributed on either side of the helical electrode and equallyspaced along the edge of the electrode. In such a configuration the meanexit velocity is about 6 m/sec. In some embodiments the maximum meanfiuid exit velocity is between about 1 m/sec and about 20 m/sec.

The above operating parameters are not intended to be limiting. Forexample, the inflation pressure can be between about 0.5 atm (or less)and about 10 atm, the flow rate can be between about 1 mL/min to about50 mL/min, and any suitable number of apertures with any suitable sizecan be incorporated into the device. Apertures may be of the same sizeor of different sizes and may also be uniformly or non-uniformlydistributed through and/or about the electrode. The apertures are sizedsuch that the total resistance of the set of apertures is appropriate tomaintain the pressures defined herein internal to the inflatable elementat the desired flows described herein. Alternatively, the totalresistance is such that the desired flows described herein aremaintained at the desired pressures described herein. The totalresistance for the parallel combination of apertures is calculated asthe inverse of the sum of the inverses of the individual apertureresistances.

The system shown also includes pressure sensor 332, which is adapted todetermine if the pressure rises above or below threshold limits. If thefluid pressure rises above an established limit, the controller shutsoff the RF energy, and fluid pump 330 is automatically shut off. Thepressure can elevate if one or more of the apertures become blocked,preventing fluid from passing out of the balloon, which can prevent theelectrode from being cooled sufficiently. Controller 324 therefore runsfluid pump 330 in a binary manner, either open-flow or off.

The system as shown also includes a temperature sensor 129 secured tothe catheter within the inflatable element. If the seared temperature ofthe fluid is above a threshold limit, the fluid will not properly coolthe electrode. If the sensed fluid temperature is above a thresholdlimit, control unit 324 is adapted to cease RF current delivery. Thefluid temperature in the balloon can rise if one or more apertures areblocked, preventing the electrode from being properly cooled and alsoincreasing the risk of charring. The fluid pressure generally will riseabove a threshold limit if this occurs as well. In some embodiments thesystem has only one of the temperature sensor and pressure sensor.

The system may also include bubble sensor 334, which is adapted to sensebubbles in the fluid line and communicates with control unit 324 to shutoff pump 330 if bubbles of sufficient volume are detected.

The system can also include a flow sensor to determine if the flow ratehas gone below or above threshold limits. RF energy delivery isautomatically stopped and the pump is automatically shut down if theflow rate goes above or below the threshold limits.

In an alternate embodiment to that of FIG. 6 the constant flow controlof the system may be replaced by constant pressure control. In such asystem the reservoir 326 may be maintained at a pressure within theprescribed pressure range using, for example without limitation, an IVbag pressure cuff or other suitable means, and the pump replaced by aflow sensor or flow controller. In such a system pressure is maintainedat a substantially constant level within the prescribed range and flowrate monitored. When flow rate falls outside of the proscribed range theRF power delivery is terminated.

In general, using a greater number of smaller holes providessubstantially the same resistance as a fewer number of larger holes, butmean fluid exit velocity is diminished.

FIG. 8 illustrates a portion of an embodiment of an RF delivery devicewherein the expandable portion has a general dumbbell configuration, andenergy is delivered through the conductive fluid to the tissue. RFdelivery device 210 includes expandable portion 222 that comprisesinflatable element 216 on which is disposed conduction material 218 witha helical configuration. The catheter has guiding element lumen 236 andirrigation lumen 228. A conductive layer and an insulation layer aredisposed on the catheter as in the embodiment in FIGS. 1-5. The proximaland distal portions of inflatable element 216 have diameters that aregreater than the intermediate section, such that the expandable portionhas a general dumbbell shape. When inflated, larger diameter proximaland distal ends of the expandable portion 214 contact the vessel wall,while space is left between the cylindrical section 222 of theexpandable element and the vessel wall as illustrated in FIG. 8. Theirrigation fluid flowing through irrigation apertures 238 fills thespace between the cylindrical section 222 and tissue, and current fromthe helical electrode is carried through the conductive irrigation fluidand into the adjacent tissue. In this configuration the helicalelectrode does not contact tissue directly, therefore the uniformity ofheating is improved and the risk of charring or overheating the tissueis reduced.

Device 210 is also adapted to query the nervous tissues adjacent to thedevice, but need not include this functionality. Device 210 includesnerve conduction electrodes 215 located on the outer surface of thedumbbell shaped proximal and distal ends of the expandable portion 214.In use, an electrical signal, typically a low current pulse or group ofpulses is transmitted to one of the conduction electrodes. This triggersa response in adjacent renal nerves, which then travels along the nervesand at some time “t” later is sensed by the opposite electrode when thesignal is traveling in the appropriate direction. By alternating whichelectrode is used as the exciter and which the sensor, both changes inefferent and afferent nerve conduction in the renal nerves may bemonitored as a function of RF treatments induced by the RF electrode.The conduction electrodes are wired to the sensing circuits in thecontroller via wires traveling within the catheter shaft, as in theirrigation lumen, or additional lumens (not shown), or multipleconductors may be applied to the outer surface of the shaft (not shown).

FIG. 9 illustrates the delivery device 210 in a delivered, or expanded,configuration within a renal artery. Areas 1005 indicate tissue treatedby the application of RF energy delivered via the helical electrode. Anarea 1005 adjacent to conductor 218 surrounds a renal nerve 1004.Irrigation fluid movement is shown by the arrows. The fluid enters theinflatable element 210 at irrigation port 230 as shown by arrows 1006.The fluid then flows out of inflatable element 216 at irrigationapertures 238, shown by arrows 1007. The fluid then flows pastconduction electrodes 215 into the blood stream, shown by arrows 1008.

In use, the dumbbell configuration creates a small space between thehelical electrode and the arterial wall. The irrigation fluid, such assaline, can be used to act as a conductor and transfer energy from theelectrode to the tissue. In such a system, the impedance variations, atthe interface between the tissue and the electrode, associated withsurface irregularities and variations in contact between the electrodeand tissue will be minimized. In this manner the fluid can act both tocool the electrode and to transfer energy to tissue. The thin layer offluid between the electrode and tissue can also prevent sticking and addlubrication.

Unless specifically stated to the contrary, the embodiment of FIG. 7includes features associated with the embodiment from FIG. 4.

The configuration of RF delivery device 210 is less dependent onconsiderations listed above with respect to the embodiment in FIG. 4 asthe irrigation fluid does not directly impinge on the treatment tissueand is allowed circulate in the space between the vessel wall and thecylindrical central section 222. Such a configuration additionallyrequires less irrigation fluid to prevent charring as the electrode 129does not contact the tissue directly.

In use, the embodiment from FIG. 5 is used to create a discontinuoushelical burn pattern formed of a plurality of discrete burn areas in thetissue. Ihe helical burn pattern is formed during a single treatmentsession and does not require the device be moved to create the pluralityof discrete burn areas.

FIG. 10 is a photograph of an RF delivery device 410 on top of a pieceof heart tissue 500 which has been ablated with RF energy delivered by adevice similar to that in FIG. 4 and a system similar to that of FIG. 6.The heart tissue was originally cut as a cylinder into the core of whichthe distal end 406 of the RF delivery device 410 was deployed. RF energycomprising a signal of 400 KHz at 40 volts and 40 watts was thendelivered to the tissue. The cylinder of tissue was then cut along itslength so that the inner surface of the tissue cylinder could bevisualized. Helical burn zone 501 was created by helical electrode 419.The burn zone has the same configuration as the helical electrode.

One aspect of the disclosure is a method of manufacturing RP deliverydevices. FIGS. 11A-11H illustrate a method of manufacturing a portion ofthe RF delivery device 110 from FIG. 4. In FIG. 11A, catheter 126 isprovided and can be any suitable catheter or other elongate device, suchas a sheath. For example, catheter 126 can be an extruded material, andoptionally can have a stiffening element therein such as a braidedmaterial. In this embodiment catheter 126 is extruded with a guideelement lumen and an irrigation lumen formed therein (not shown), andthe irrigation port is formed therein (not shown). The irrigation lumenis closed off at the distal end of the catheter to prevent fluid fromescaping the distal end of catheter, but the irrigation lumen can stopat the irrigation port raher than continuing further towards the distalend.

Inflatable element 116, which can be an inflatable balloon, is thensecured to the exterior of catheter 126 using any suitable techniquesuch that irrigation port 130 is disposed within inflatable element 116.Next, mask 60 is applied or slid over inflatable element 116. The maskis configured such that it covers areas where the conductive material isnot to be deposited and is open where conductive material is to beapplied. In FIG. 11C, mask 60 is configured with open area 61 to allowfor the deposition of a conductive element 118 in a helicalconfiguration. Inflatable element 116 is then inflated with a suitableinflation fluid (e.g., liquid or gas) delivered through the irrigationlumen and out port 130 to expand, or inflate, inflatable element 116, asshown in FIG. 11C. Additionally, mask 60 is typically configured to maskthe distal transition section of the expandable portion and the catheterdistal to the expandable portion. After mask 60 is applied, conductivematerial 118 is then deposited, in a single deposition step, ontosubstantially all of catheter 126, portions of inflatable element 116,and mask 60. This forms a conductive material layer on substantially allof catheter 26, proximal portion of inflatable element 116, and in thehelical pattern on inflatable element 116. After the conduction material118 is deposited in the single step and allowed to dry sufficiently andor cure, inflatable element 116 is deflated and the mask 60 is removed.As shown in FIG. 11F, a second mask 70 is then applied over those areasof conductive material 118 which are intended to deliver energy directlyto the tissue in the energy delivery pattern, which is the helicalpattern. The inflatable element 216 is then re-inflated and insulationmaterial 34 is applied to substantially the entire device in a singledepositing step as shown in FIG. 11G. This forms an insulation layer onsubstantially the entire conductive material already deposited oncatheter 126, the proximal portion of the inflatable element, and theintermediate portion of the inflatable element where mask 70 is notdisposed. Next, after appropriate drying and or curing the inflatableelement is deflated and the mask 70 removed as shown in FIG. 11H. Aftermask 70 is removed, shaft 126, and proximal transition section ofinflatable element is encapsulated by conductor 118 which are in turnencapsulated by dielectric 134, while helical conductive electrode 118on the inflatable element is not covered with dielectric. The irrigationapertures are then formed, such as by laser drilling.

In some embodiments of manufacturing the device, the layers ofconductive material and insulation material are between about 0.0001 andabout 0.001 inches thick. In some embodiments the conductive layer isabout 0.0003 inches thick. In some embodiments the insulation layer isabout 0.0005 inches thick.

Alternate methods for deposition of the conductor and/or the dielectriclayers which that can be used and do not require masking include ink jetand or pad printing techniques.

These methods of manufacturing form a unitary conductor. A “unitaryconductor” as described herein is a single conductive materialcomprising both a conduction element and an electrode element whereinthe conductive element communicates energy between the controller andthe electrode element.

The conductive and insulation materials can each be deposited onsubstantially all of elongate portion 112 (excluding the portion withinexpandable portion 114) and expandable portion 114 in a single step,reducing the time necessary to form the conductive and insulationlayers, respectively. This can also simplify the manufacturing process.To deposit the conductive and insulation material, the device can besecured to a mandrel and spun while the material is deposited, or thedevice can be secured in place while the device used to deposit thematerial is moved relative to the device, or a combination of the twosteps. “Single step” as used herein includes a step that applies thematerial without stopping the deposition of material. For example, theconductive material can be deposited on substantially all of thecatheter proximal to the inflatable element and to the inflatableelement in a single step. “Single step” as used herein also includesapplying a second or more coats to the elongate portion and theexpandable portion after initially ceasing the deposition of material.For example, a process that applies a first coat of conductive materialto substantially all of the catheter proximal to the inflatable elementand to the inflatable element, followed by a ceasing of the deposition,but followed by application of a second coat to substantially the entireportion of the catheter proximal to the inflatable element and to theinflatable element, would be considered a “single step” as used herein.Some previous attempts to form a conductive material on an elongatedevice formed one or more discrete conductive elements on the elongatedevice, thus complicating the deposition process. These and otherattempts failed to appreciate being able to form a single layer ofconductive material on substantially all of the catheter or otherelongate device. These attempts failed to appreciate being able to formsingle layer of conductive material on the catheter and an electrodeelement on an expandable element in a single step.

By disposing the conductive material on the external surfaces of thecatheter and inflatable element in a single step, the creation ofelectrical junctions is avoided. For example, a junction need not beformed between the conductive material on the catheter and theconductive material on the inflatable element. As used herein,electrical junction refers to a connection created between twoconductive materials, either the same or different materials, thatallows an electrical signal to be conducted from one material to theother.

The inflatable element is, in some embodiments, an inflatable balloonthat is adapted to be inflated upon the delivery of a fluid through theirrigation lumen and out of the irrigation port. In the embodiment inFIGS. 1-11, the inflatable element is a balloon made of non-elastic, ornon-compliant, material, but it can be a compliant, or elastic, materialas well. Materials for a non-compliant balloon include, withoutlimitation, polyethylene, polyethylene terephthalate, polypropylene,cross-linked polyethylene, polyurethane, and polyimide. Materials for acompliant balloon include, without limitation, nylon, silicon, latex,and polyurethane.

In some embodiments of the embodiment in FIG. 4, the length of thecylindrical intermediate portion of the inflatable element is betweenabout 1 cm and about 4 cm. In some embodiments the inflatable elementhas a diameter between about 4 mm and about 10 mm. In some particularembodiments the length of the intermediate portion of the inflatableelement is about 20 mm and the diameter is about 5 mm to about 7 mm.

The conductive material can be deposited onto the catheter and/orexpandable portion. Methods of depositing include, without limitation,pad printing, screen printing, spraying, ink jet, vapor deposition, ionbeam assisted deposition, electroplating, electroless plating, or otherprinted circuit manufacturing processes.

In some embodiments the conductive material deposited is an elastomericink and the dielectric material is an elastomeric ink. They can besprayed on the respective components. In some embodiments theelastomeric ink is diluted with an appropriate diluent to an appropriateviscosity then sprayed in a number of coats while the delivery device isrotated beneath a linearly translating spray head.

Conductive materials that can be deposited on the device to form one ormore conductive layers of the device include conductive inks (e.g.,electrically conductive silver ink, electrically conductive carbon ink,an electrical conductive gold ink), conductive powders, conductivepastes, conductive epoxies, conductive adhesives, conductive polymers orpolymeric materials such as elastomers, or other conductive materials.

In some embodiments the conductive material comprises an elastomericmatrix filled with conductive particles. Elastomeric components includesilicones and polyurethanes. Conductive materials are conductive metalssuch as gold or silver. Conductive inks that can be used are conductiveink CI-1065 and CI-1036 manufactured by ECM of Delaware Ohio. This inkis an extremely abrasion resistant, flexible, and highly conductiveelastomeric ink. The ink has the following properties: 65% solids in theform of silver flakes; 0.015 ohms/square (1 mil (0.001 inches) thick);and a 10 minute cure time at 248 F.

The electrodes described herein can also be used as a temperaturesensor. Ablative electrodes are routinely used in wide variety ofsurgical procedures. Many of these procedures are performedpercutaneously, and a subset are performed endovascularly. In many ofthese procedures it is customary to incorporate provisions to monitorthe temperature of the ablative electrodes. This temperature informationis then used in some fashion as an input in a control scheme to limitthe maximum temperature the electrode is allowed to attain. In thisfashion a number of mechanisms, that may be deleterious to the desiredoutcome, may be controlled and or limited. Some of these effects, whichin some circumstances are considered deleterious are, tissue charring,creation of steam, and the resultant uncontrolled, rapid, or largechanges in interface impedance.

The temperature monitoring is typically carried out by incorporating andmounting some form of a temperature sensor such as a thermocouple, anrdt, or a thermistor in proximity to, or on, the electrode.

The electrodes are typically comprised of metals or metal alloys whichare either deposited as metals directly through various metal depositionprocedures such as, but not limited to physical or chemical metal vapordeposition, or applied as a component in a matrix such as but notlimited to organic polymers in the form of an ink. Such inks aredeposited in many ways, a few of which are, screening, spraying, inkjetting.

Metals, metal alloys, and other metal compound have resistancecharacteristics which are dependent on temperature, typically called thetemperature coefficient of resistance or “tempco.” The magnitude andcharacteristics of these effects varies and is often used in devicessuch as a resistance temperature detector “RTD”, such as a platinumrtd's, or in positive temperature coefficient “PTC” or negativetemperature coefficient “NTC” thermistors.

The systems herein can therefore altentatively monitor temperature byusing the inherent tempco of the electrode itself as a way of monitoringits temperature and or controlling its impedance and therebyself-limiting its power output and thereby its temperature.

FIG. 12 represents an embodiment of a system similar to that of FIG. 6represented by the resistances of the various elements. The delivery RFlead which runs down catheter is represented as resistance 626 and theelectrode is represented by resistance 619. In this embodiment there isan additional conductive element running along the catheter shaft whichis a return line represented by resistance 650. In use the leads whoseresistances are represented by 626 and 650 may be sourced in parallelwhen RF is delivered to electrode 619 and addressed separately when usedto characterize the resistance and hence temperature of the electrode619. Alternatively one of them may be used solely for the purpose ofmonitoring temperature and therefore left open circuited when RF isbeing delivered. The design of the delivery system and electrode will besuch that the impedance 640 of the patient will be orders of magnitudegreater then the impedances for the delivery leads 626, 650, and theelectrode 619. In one embodiment impedance 619 will be considerablygreater than 626 or 650, or in some cases the parallel combination of626 and 650.

In one embodiment the electrode is comprised of a layer of platinum andthe temperature of the electrode may be characterized by monitoring thevoltage drop across the series resistances 626, 619, 650. This may bedone intermittently, interspersed in the delivery of the RF energy. Asthe electrode heats, its resistance will increase in a well-known andrepeatable fashion. As the leads 626 and 650 have lower resistance andwill not self-heat appreciable, the change in resistance will byprimarily due to the heating of electrode 619 and variation in itsresistance. Many other scenarios will be understood to those skilled inthe art.

An alternate arrangement which relies on the use of a PTC for theelectrode relies on the rapid change in resistance of the electrode pasta particular set point which is a function of the composition of theelectrode. In this configuration the tempco of the electrode isrelatively small, for example, below about 40 C but above about 40 C. Inthis temperature range the tempco rapidly increases thereby limitingdelivered power in a voltage-limited RF configuration. Many alternateembodiments will be understood by those skilled in the art.

FIG. 13 illustrates an alternative configuration in which a capacitor648, inductor (not shown), or both may be incorporated in the circuit.In one embodiment the circuit may incorporate only one source lead 621and the inherent resonance of the circuit which will depend on thevarying impedance of the electrode resistance 623.

In yet another alternative the tempco associated with a conductive inksuch as the ECM CI-1036 may be used. Experimentally the ECM CI-1036demonstrated a 0.1% increase in impedance per degree over the range of30 C to 60 C.

As described above, devices capable of ablating renal nerves surroundingthe renal arteries are useful in treating hypertension. The devicedisclosed in FIG. 16 is another embodiment of a device adapted for suchpurpose. The device described herein comprises a bipolar electrode pairdisposed on the outer surface of an expandable structure comprised of aninflatable balloon. A bipolar electrode pair provides for both a morecontrolled burn and a shallower burn than a comparable monopolarelectrode. The device is configured for endovascular delivery to a renalartery. Each of the individual electrodes comprising the bipolar set isin turn comprised of a unitary electrode/conductor.

Referring to FIG. 16, detailed description of the distal features of anembodiment of the device is as follows. The distal portion of a bipolarRF delivery device 810 includes an expandable section 850 including aballoon, and a catheter shaft section 820 including an inner shaft 830and an outer shaft 840. The inner lumen of the inner shaft 830 includesa guidewire lumen 822. The annular gap between the inner and outershafts includes an irrigation lumen 821. The outer shaft 840 alsoincludes an irrigation outflow 812 (e.g., an irrigation port) locatednear its distal end such that it is disposed within the balloon. Atemperature sensor 811 may be located within the balloon 850 andinterconnecting leads of the temperature sensor 811 may be routedthrough the irrigation lumen outflow 812 and irrigation lumen 821.

Prior to assembly, a conductive material is deposited on substantiallythe entire inner shaft 830. A dielectric material is then deposited onthe conductive material except at the distal most end of the inner shaft830. The inner shaft 830 is then lilted within the outer shaft 840 andthe two are affixed to one another such that the inner shaft 830 extendsbeyond the most distal portion of the outer shaft 840 and the balloon850. The dielectric on the inner shaft 830 is deposited on at least theportions of the surface of the conductor on the inner shaft 830 thatwould contact irrigation fluid, thus preventing the conductive materialon the inner shaft 830 from coming into contact with irrigation fluid.The distal end of the inner shaft 830, which extends distal to the outershaft 840, is not coated with dielectric. This allows the inner shaft830 to be in electrical communication with the inner sourced electrodeas described below.

Next, the outer shaft 840 and balloon 850 are coated with an elastomericink, and then, subsequently, by a dielectric as described above. Theconductive coating is deposited on the outer shaft 840, all or a portionof the proximal cone 843 of the balloon 850, and on the balloon 850,forming a conductive material that includes an outer sourced spiralelectrode 842. This conductive material can be deposited in a uritarymanner, as is described above and in the materials incorporated byreference herein. Conductive material is also deposited on the mostdistal section of the shaft assembly, the distal cone portion 833 of theballoon 850, and the balloon 850, forming a conductive material thatincludes an inner sourced electrode 832. This conductor can also beformed in a unitary manner. The conductive material that forms the innersourced electrode can be the same material that is used for the outersourced electrode. When the distal conductor (which includes the innersourced electrode 832) is formed, it interfaces electrically with theconductor on the inner shaft 830 that extends distal to the balloon 850.The conductive materials can be selected such that when the conductivematerials are deposited, the interface is a single layer of the samematerial rather than two distinct layers. The conductor and dielectricstructures can be fabricated as described above. When used in bipolarmode, energy passes from one spiral electrode 832 or 842, through renalnerve tissue, to the other electrode. The electrodes 832, 842 can beused in a bipolar manner, or each electrode can be used in monopolarmode. Bipolar mode can be used if the tissue burn need not be in deep asmay be needed if using a monopolar mode. Bipolar mode generally allowsmore control in the tissue burn. Additionally or alternatively, theelectrodes 832, 842 can be used together as a single monopolar electrode(e.g., by feeding both electrodes with the same frequency and RF energysuch that the electrodes appear to be one electrode).

In an alternative embodiment, the inner shaft is not coated with aconductor (or dielectric) and, instead, a wire extends through theirrigation lumen, and interfaces the conductor that includes the innersourced electrode.

Although not shown in FIG. 16, irrigation ports as described above canbe situated such that they pass through the electrode structures, sitadjacent to the electrode structures such as in the space between themor exterior to the pair, or both.

One or more radio opaque markers 813 may be affixed to the outer shaft.

In embodiments, an anesthetic solution may be introduced in conjunctionwith, or independent of, the irrigation fluid, to potentially reducepain or discomfort associated with renal denervation treatment. Suitableanesthetics include lidocaine, articaine, bupivacaine,cinchocaine/dibucaine, etidocaine, levobupivacaine,lidocaine/lignocaine, mepivacaine, prilocaine, ropivacaine, trimecaine.Other possibilities include, but are not limited to drugs which targetneuropathic pain such as: butyl-para-aminobensoate (Butamben

), an ester local anesthetic, bupivacaine microspheres, SNX-111 (aselective calcium channel blocker), nicotinic acetylcholine receptoragonists such as ABT-594, and adrenergic blocking agents such asguanethidine or reserpine. Lidocaine is particularly suitable because itis approved for arterial use and the systemic limits are understood. Inaddition, lidocaine is a small molecule, which may result in fasterdiffusion through the artery wall. A contrast agent may be incorporatedin the solution to enable visualization of the delivery of theanesthetic solution and confirmation that the targeted nerve structurehas been engulfed by the solution. The contrast agent can be mixed withthe anesthetic solution before the mixture is conveyed through thecatheter. Examples of suitable contrast agents include thosetraditionally used for angiographic imaging such as the non-ionicfluoroscopic contrast agents that are iodate based (e.g., UltraVist300).

Several factors for consideration in the delivery of an anestheticsolution as part of a renal denervation procedure include the ability tocontrol the total dose or volume delivered and the ability to controlthe residence time or period the anesthetic solution remains at thetreatment site while considering parameters relating to mobility, tissuedensity, etc. to ensure the anesthetic solution reaches the target renalnerves. The total volume delivered may vary depending on the targetedtissue and the anesthetic used. For lidocaine, the volume may be about10 ml for a 1% solution.

Various approaches for delivery of the anesthetic solution to targetnerve tissue for alleviating pain during renal denervation include,e.g., a high pressure delivery approach and/or a dwell time approach.The targeted nerve tissue may include nerve tissue in the intima, media,adventitia, and/or surrounding tissue of a renal artery. Generally, ahigh pressure delivery approach involves delivering anesthetic solutionunder relatively high pressure against the renal artery wall to causepassing within and/or through the wall via the vaso vasorum andinfiltrate the targeted nerve tissue. With the dwell time approach, theanesthetic solution is maintained within the renal artery for a periodof time to eventually diffuse or otherwise migrate through the vesselwall to at least partially engulf the targeted nerve tissue. Any of theaforedescribed embodiments of the energy delivery devices may bemodified to deliver the anesthetic solution via the high pressure ordwell time approaches.

Referring now to FIGS. 17-18, there is illustrated an energy deliverysystem 2000 for delivering an anesthetic solution under high pressure tothe renal vasculature (e.g., the renal artery or a renal vein), suchthat the solution enters the vessel wall and potentially migrate to therenal nerve structure surrounding the artery or vein. The energydelivery system 2000 includes a catheter 2002 having a catheter hub2004, an elongate catheter member 2006 extending distally from the hub2004 and an expandable treatment member 2008 mounted to the cathetermember 2006. The elongate catheter member 2006 and the treatment member2008 may be substantially similar to the elongate portion 12 and theexpandable portion 14, respectively, of the energy delivery device 10disclosed in connection with FIGS. 1A-2. The hub 2004 may include one ormore ports for reception of a guidewire, introduction of fluids or thelike. In embodiments, the catheter hub 2004 includes a guidewire port2010 and a fluid port 2012. The guidewire port 2010 is in communicationwith a guidewire lumen 2014 extending through the catheter member 2006.The fluid port 2012 is in fluid communication with a fluid lumen 2015extending through the catheter member 2006 and communicating with thetreatment member 2008 through a fluid opening 2016. The fluid opening2016 extends through the wall of the catheter member 2006 andcommunicates with an interior portion of the treatment member 2008.

The energy delivery system 2000 further includes an irrigation orinflation source 2018 and associated irrigation fluid line 2020. Theirrigation source 2018 includes fluids for expanding the treatmentmember 2008 and/or for cooling tissue and/or for cooling the conductivematerial on the treatment member 2008. Any of the aforementionedirrigation fluids may be utilized.

The energy delivery device 2000 further includes a source of anestheticsolution 2022 and associated anesthetic fluid line 2024. The anestheticsource 2022 may include any of the anesthetic solutions mentionedhereinabove or other anesthetic solutions.

The energy delivery system 2000 may further include a valve 2026 whichis in line with the irrigation fluid line 2020 and the anesthetic fluidline 2024 to permit selective infusion of either the irrigation fluid orthe anesthetic solution. The valve 2026 may be manually operated or maybe controlled via automation (e.g., programmable) to switch between anirrigation mode for supplying irrigation fluids from the irrigationsource 2018 and an anesthetic mode for supplying the anesthetic solutionfrom the anesthetic source 2022. A pump 2028 may be in fluidcommunication with the valve 2026 to deliver the irrigation fluid or theanesthetic solution under pressure to the fluid lumen 2012 via a supplyline 2030.

The energy delivery system 2000 may also include a controller,identified schematically as reference numeral 2032, with associatedlogic, software or circuitry for controlling operation of the pump 2028and/or the valve 2026. The software may contain at least one program forautomated operation of the pump 2028 and/or the valve 2026 and/or mayoperate in response to various parameters detected during operation. Forexample, a sensor 2034 may be in communication with the feed line 2030extending from the pump 2028 to the fluid port 2012 of the catheter hub2004 to detect flow rate (e.g., a flow rate sensor) or pressureassociated (e.g., a pressure sensor or transducer) with the irrigationfluid or anesthetic solution delivered to the expandable treatmentmember 2008. The activity of the pump 2028 (e.g., an increase ordecrease in pump speed, output or flow rate) may be controlled by thecontroller 2032 based at least in part on parameters detected by thesensor 2034. Signals transmitted between the controller 2032 and thevalve 2026, the pump 2028 and the sensor 2034 are represented as signals“v1”, “v2”, “v3”, respectively.

The expandable treatment member 2008 may be any of the expandableportions described hereinabove. In embodiments, the treatment member2008 includes a balloon or inflatable element 2036, a helical electrode2038 on the outer surface of the inflatable element 2036 for deliveringenergy to the renal nerve tissue and non-conductive segment or material2040 surrounding the helical electrode 2038. The treatment member 2008further includes a plurality of apertures 2042 defined in the inflatableelement 2036 and/or the helical electrode 2038. In FIGS. 17 and 18, theapertures 2042 are present in both the helical electrode 2038 and thenon-conductive segment 2040 of the inflatable element 2036 forillustrative purposes. The apertures 2042 may have pore sizes rangingfront about 0.5 mil to about 10 mil. The pore size, pore density and thethickness of the inflatable element 2036 may be selected to deliver theanesthetic solution at a pressure sufficient to pass through the renalartery wall for dispersion into the renal artery wall and possibly tosurrounding renal nerves. The pressure of the anesthetic solution mayvary, but in embodiments, a range of pressure within the inflatableelement 2036 is between about 1 atm to about 4 atm. When desired, arelatively high pressure may be used to deliver anesthetic solution at avelocity sufficient to cause the solution to enter the renal artery andultimately migrate to targeted nerves, including those in the media,adventitia, or surrounding tissue.

In operation, with reference to FIG. 18, the treatment member 2008 ispositioned at the targeted location within the renal artery “a” or otherrenal vasculature. The anesthetic solution is then delivered bypositioning the valve 2026 either manually or automatically via thecontroller 2032, to the anesthetic mode. The pump 2028 is activated todeliver the anesthetic solution to the fluid port 2012 through theinflation lumen 2015 and within the interior of the inflatable element2036 for delivery through the apertures 2042 under high pressure. Theanesthetic solution “s” delivered within the pressure range identifiedhereinabove will enter and pass within and/or through the renal arterywall “a” and migrate to the renal nerve fibers or tissue “t” via thevasculature in the vessel wall. During application of the anestheticsolution “s”, the pressure within the inflatable element 2036 orinflation lumen 2015 may be monitored with the sensor 2034, which sendsa signal back to the controller 2032. For instance, in the event thesensed pressure is below a threshold value potentially indicating thatthe anesthetic solution “s” is being delivered from the apertures 2042at a relatively low pressure where diffusion is the primary manner inwhich it passes within and/or through the vessel wall, the pump or flowrate may be increased to increase the flow rate through the vessel toenhance the passage of the anesthetic within and/or through the bloodvessels in the vessel wall. Similarly, if the sensed pressure is above athreshold value, flow rate delivered by the pump 2028 may be decreasedto an acceptable range.

Once the renal nerves are desensitized by the anesthetic solution “s”,the valve 2026 can be switched to the irrigation mode and the controller2032 activated to introduce irrigation and/or inflation fluids throughthe inflation lumen 2015 and within the inflatable element 2036. In theirrigation mode, the flow rate and pressure may be reduced relative tothe anesthetic mode to a pressure, e.g., below 1 atm. The inflatableelement 2036 expands to position the helical electrode 2038 inapposition with the wall of the renal artery “a”. The system isenergized and energy is delivered through the helical electrode 2038 totreat and/or denervate the renal nerves. The irrigation fluid cools theelectrode 2038 and surrounding tissue as described hereinabove.

If during treatment, it is determined that another injection ofanesthetic solution “s” is warranted, the irrigation fluid within theirflatable element 2036 may be drained either passively or actively fromthe inflatable element 2036, and the anesthetic fluid delivered directlyto the uninflated inflatable element 2036 for delivery to the nervetissues through the apertures 2042. In some embodiments, the anestheticsolution may be prefilled within the inflatable element 2036, and usedto purge the system 2000 prior to use. This may present a more efficientand faster method for delivery of the anesthetic solution “s’.

In embodiments, the helical electrode 2042 may be used to enhance thedelivery of the anesthetic solution “s” through electrophoresis. Forexample, the helical electrode 2042 can be used to deliver a low currenthigh voltage creating a charge gradient across the tissue, whichincreases the infusion rate of ionic anesthetic solutions “s” throughthe wall and into the nerves. In some embodiments, the generatorassociated with the controller 2032 can have two settings. The firstsetting can be for the delivery of a high voltage low current signal tothe electrode 2038 during delivery of the anesthetic solution “s” toestablish the electrophoretic environment. The second setting can be forthe delivery of RF energy for nerve ablation. The use of electrophoresisto improve infusion of anesthesia into the tissue can be used with anyof die single electrode helical electrode configurations described inFIGS. 1-15 and 17-18 and/or the double electrode configuration of FIG.16. In embodiments, the first setting of the generator also may beutilized to deliver non-RF voltage to excite the surrounding renalnerves. When the patient indicates to the clinician that the patient nolonger feels the excited nerves, the clinician is apprised that thenerve tissue may be sufficiently anesthetized for the denervationtreatment.

In embodiments, the source of anesthetic solution 2022 and the pump 2028may be replaced with a syringe 2100 containing the anesthetic solution“s” (FIG. 17). The syringe 2100 may be introducible within or coupled tothe fluid port 2012 of the catheter hub 2004 and delivered to theinflation lumen 2015 and the inflatable element 2036 of the treatmentmember 2008 for dispensing through the apertures 2042. The syringe 2100may be manually activated. The flow of the anesthetic solution “s” maybe moderated by the clinician via monitoring of the pressure via thesensor 2034 to provide delivery of the anesthetic solution “s” at thedesired flow rate and high pressure sufficient to pass within and/orthrough the wall of the renal artery “a” and migrate to the targetedrenal nerve tissue “t”. The syringe 2100 may have gradations to assistthe clinician in determining the volume of anesthetic solution “s”delivered to the inflatable member 2036. Additionally or in thealternative, the syringe 2100 may be filled with a predetermined volumeof anesthetic solution “s” corresponding to a maximum volume intendedfor use during the treatment. Other fluid displacement mechanisms bothmanual and automated for delivering the anesthetic solution “s” are alsowithin the scope of this disclosure.

As indicated hereinabove, in certain embodiments, instead of, or inaddition to, the high pressure delivery of anesthetic solution to therenal nerves, a dwell-time approach may be utilized for delivery ofanesthetic solution to the renal nerves. In accordance with thisapproach, the anesthetic solution is caused to dwell for a sufficientperiod of time at the treatment site such that the anesthesia solutionhas time to passively diffuse or otherwise move through the wall of therenal vasculature, e.g., the renal artery “a” or a renal vein.Increasing the dwell time of anesthetic solution at the treatment sitecan effectively increase the volume of delivered anesthesia that passeswithin and/or through the wall of the renal artery. This can, forexample, result in delivery of an effective amount of anesthetic whileusing only a small portion of the overall systemic dose of theanesthetic solution.

In embodiments, the anesthetic solution may incorporate or be infusedwith microbeads. For example, microbeads can be saturated in ananesthetic such as lidocaine. The saturated microbeads can be mixed withsaline to form the anesthetic solution and the solution can be deliveredto the inflatable member 2036. The anesthetic solution will leave themicrobeads as the microbeads migrate through the vessel wall of therenal artery “a” acting as a localized drug source delivering theanesthetic for a predetermined period of time during their migration andwhen at rest. This may increase the amount of time the anesthetic ordrug is active in the area. This can facilitate the use of lessanesthetic solution and allow for the anesthetic to be active for alonger period of time as compared to an injected drug, which getsremoved by the lymphatics.

In the alternative, the dwell time of anesthesia delivery may beincreased by altering the rate of delivery of the anesthetic solutioninto the inflatable element of the treatment member thereby slowing theinfusion rate into the renal artery. One procedure using an anestheticsolution containing lidocaine for treating renal arteries prior to an RFablation for the treatment of hypertension includes a slow infusion of2-4 ml of a 1% lidocaine solution (20-40 mg lidocaine) with an upperlimit of a bolus 10 ml (100 mg lidocaine). Referring now to FIG. 19, oneembodiment of an energy delivery system 2200 adapted for delivering ananesthetic solution through a dwell-time approach in conjunction withenergy delivery is illustrated. The configuration of the catheter 2202of the system 2200 is substantially similar to the embodiment of FIGS. 8and 9, and reference is made thereto for particulars of the cathetermember 2202 and the expandable treatment member 2204. The system 2200may incorporate features of the system 2000 discussed in connection withFIGS. 17 and 18 for providing automated control of infusion rate,pressure and/or delivery volume. The treatment member 2204 includes aninflatable element 2206 having enlarged proximal and distal occludingend segments 2208, 2210 and an intermediate or central segment 2212disposed between the proximal and distal end segments 2208, 2210. Inembodiments, the inflatable element 2206 is a single balloon member. Theenlarged end segments 2208, 2210 define a greater cross-sectionaldimension or diameter than the intermediate segment 2212 when in an atleast partially expanded condition as shown in FIG. 19, thereby defininga general dumbbell shape to the expanded inflatable element 2206. Inaccordance with this embodiment, the spacing defined between theintermediate segment 2212 of the inflatable element 2206 and the vesselwall of the renal artery “a” provides a reservoir “r” for receiving theanesthetic solution “s”. Thus, upon expansion of the inflatable element2206, the end segments 2208, 2210 engage the interior wall surface ofthe renal artery “a” while the intermediate segment 2212 is in a spacedrelation from the interior wall surface. The end segments 2208, 2210 aredimensioned to substantially occlude the interior of the renal artery“a” thereby enclosing the reservoir “r”. Anesthetic solution “s” isintroduced within the irrigation lumen 2214 of the catheter member 2202and delivered through the irrigation port 2216 under relatively lowpressure, e.g., less than about 2 atm or less than about 1 atm. Theanesthetic solution “s” passes through the apertures 2218 within theinflatable element 2200 and/or in the helical electrode 2220. Due to thereservoir holding capacity, the anesthetic solution “s” remains incontact with the vessel wall of the rural artery “a”. Over time, theanesthetic solution “s” diffuses through the wall and into thesurrounding renal nerve tissue “t” so that the solution has its desiredanesthetic effect. In some implementations, the anesthetic solution “s”delivered to the reservoir “r” can be removed after a predeterminedtreatment period via aspiration through the irrigation port 2216 tominimize the amount, of anesthetic remaining in the patient's system.Irrigation fluid may then be delivered to the inflatable element 2206and the system energized such that the electrode 2220 delivers energy todenervate the nerve fibers. The irrigation fluid cools the electrode2220 and/or the surrounding tissue.

FIG. 20 illustrates a variation of the treatment member of FIG. 19 wherethe inflatable element 2300 includes an enlarged distal end region 2302while the main section 2304 of the inflatable element 2300 is of aconstant smaller cross-sectional dimension or diameter when in the atleast partially expanded condition of the inflatable element 2300. Withthis arrangement, a more distal region of the renal artery “a” isoccluded and anesthetic solution “s” is delivered through apertures 2306in the main section 2304 to the renal artery and the renal nerves.Although the reservoir is open adjacent ihe proximal end 2308 of theinflatable element 2300, the flow rate of the anesthetic solution “s”may be controlled to ensure a sufficient dwell time or period isachieved for the anesthetic solution “s” to pass from the reservoir tothe renal nerves. In an alternative use, the proximal end 2308 of theinflatable element 2300 may occlude a vessel wall due to the geometry ofthe vasculature in which it is positioned to substantially enclose thereservoir. For example, the proximal end 2306 maybe positioned within amore narrow area of the renal vasculature, which, upon expansion willengage and at least partially occlude the wall to enclose the reservoir.In another approach, the proximal end 2306 may be positioned adjacent acurve or bend in the renal vasculature whereby the proximal end 2306engages the curve to assist in enclosing the reservoir. As a furtheralternative, the proximal end 2306 of the inflatable element 2300 may beenlarged while the rest of the main section 2304 of the inflatableelement 2300 including the distal end region is of constant dimension ordiameter. Although the apertures 2306 are shown in the non-conductivesegment 2312 of the inflatable element 2300, the apertures 2306 mayextend through the helical electrode 2310 or through both the electrode2310 and the non-conductive segment 2312 of the main section 2304.

FIGS. 21-22 illustrate an alternate embodiment of the expandabletreatment member of FIGS. 8, 9 and 19. In accordance with thisembodiment, an inflatable element 2400 is dimensioned to transitionbetween at least two conditions depending on the fluid operationalpressure within the interior of the inflatable element 2400. At a firstoperational state or pressure depicted in FIG. 21, the inflatableelement 2400 assumes the general “dumbbell” orientation with theproximal and distal occluding end segments 2402, 2404 defining a greatercross-sectional dimension or diameter than the intermediate segment2406. At a second operational state or pressure greater than the firstoperational state depicted in FIG. 22, the intermediate segment 2406expands to generally approximate the dimension or diameter of theproximal and distal end segments 2402, 2404. The proximal and distal endsegments 2402, 2404 maintain substantially the same dimension ordiameter exhibited in the first operational state. In embodiments, theinflation element 2400 is a single balloon member where the intermediatesegment 2406 may be fabricated from a more conformable material than theend segments 2402, 2404 to permit greater expansion of the intermediatesegment 2406 when subjected to the increase pressure of the secondoperational state. In other embodiments, the end segments 2402, 2404could incorporate stiffening material or elements, such as polymericstrands, braids, woven materials, splines, or the like. The stiffeningelements would be fabricated from a material which will not interferewith the functioning of the helical electrode 2408.

In operation, a catheter member 2410 is advanced to position theinflatable element 2400 within the renal vasculature at the targetedsite. The inflatable element 2400 is inflated to assume the first stateor condition with the proximal and distal end segments 2402, 2404engaging and at least partially occluding the vessel wall with theintermediate segment 2406 spaced from the wall to define the annularreservoir “r” discussed hereinabove and shown in FIG. 21. The anestheticsolution “s” is introduced within the interior of the inflatable element2400 and communicates through the fluid port 2410 in fluid communicationwith the fluid lumen 2412 and out the apertures 2414 to at leastpartially fill the reservoir “r”. The anesthetic solution ‘s” willeventually diffuse through the wall of the renal artery “a’ distributingwithin the renal nerves “t” in the tunica intima, tunica media, andadventitia to anesthetize the tissue. Thereafter, the inflatable element2400 may be expanded to its second operational state through theintroduction of the irrigation fluid at, e.g., a greater pressure and/orflow rate, whereby the intermediate segment 2406 expands to contact thevessel wall as depicted in FIG. 22. In the second state, the helicalelectrode 2408 is in apposition with the vessel wall. Energy can bedelivered to the helical electrode 2408 to provide the desiredtreatment.

FIGS. 23-25 illustrate an embodiment of the energy delivery system wherethe treatment member 2500 includes proximal and distal occluding balloonelements 2502, 2504 with an intermediate or central balloon or inflationelement 2506 disposed therebetween. The central balloon element 2506 isa treatment balloon and incorporates the helical electrode 2508 to treatthe tissue in the aforementioned manner. The proximal and distal balloondements 2502, 2504 may be expandable independent of the central balloonelement 2506 to occlude the renal vessel and form the reservoir “r” foraccommodating the anesthetic solution “s” as shown in FIG. 24. Inembodiments, the catheter member 2509 may include a first lumen 2510(shown schematically) in fluid communication with each of the balloonelements 2502, 2504 through fluid ports 2512, 2514, respectively. Withthis arrangement, the proximal and distal inflation elements 2502, 2504are simultaneously inflated or deflated. In the alternative, proximaland distal balloon elements 2502, 2504 may be isolated from one anotherand inflated independent from each other by provision of an additionallumen (not shown). The catheter member 2509 may include a second lumen2516 (shown schematically) in fluid communication with the centralballoon element 2506 through fluid opening 2518. In embodiments, thecatheter member may include a third lumen 2519 for receiving theguidewire. The central balloon element 2506 includes a plurality ofapertures 2520 extending through its wall for delivering the anestheticsolution or the irrigation fluid. The apertures 2520 may also extendthrough the helical electrode 2508.

In operation, the expandable treatment member 2500 is positioned at thedesired location within the renal artery “a”. The proximal and distaloccluding balloon elements 2502, 2504 are simultaneously inflated withthe irrigation fluid to occlude the renal artery at upstream anddownstream locations as shown in FIG. 24. The anesthetic solution “s”may be delivered through the second lumen 2516 at a first pressure andinto the central balloon element 2506 via the fluid opening 2518. Thecentral balloon element 2506 may be at least partially inflated whilethe anesthetic solution “s” flows through the apertures 2520 within thecentral balloon element 2506 and into the reservoir “r”. For example,infusion of the anesthetic solution “s” through the central balloonelement 2506 can be controlled to limit expansion of the central balloonelement 2506 such that the annular space of the reservoir “r” ismaintained to accommodate the anesthetic solution “s”. After diffusionof the anesthetic solution “s” through the renal artery “a” and therenal nerve tissue “t”, the proximal and distal balloon elements 2502,2504 may be deflated and the central balloon element 2506 furtherexpanded via introduction of irrigation fluid to position the helicalelectrode 2508 in apposition with the wall of the renal artery “a” asdepicted in FIG. 25. The helical electrode 2508 is activated to transmitenergy to denervate the targeted nerve tissue “t”. In the alternative,the proximal and distal balloon elements 2502, 2504 may remain in theirexpanded state during treatment with the electrode 2508.

FIG. 26 illustrates an alternate arrangement of the treatment member ofFIGS. 23-25. In this embodiment, the treatment member 2600 includescentral or main inflation element 2602 of generally cylindricalconfiguration and proximal and distal axially spaced inflation elements2604, 2606. In embodiments, the inflation elements 2602, 2604, 2606 areindividual balloon members. The proximal and distal axially spacedinflation elements 2604, 2606 may be toroidal or generally donut shapedand mounted about, or directly to, the proximal and distal ends of themain inflation element 2602, i.e., about the outer surface of the maininflation element. The first and second axial inflation elements 2604,2606 may be in fluid communication with the irrigation fluid via tubing,identified schematically as reference numeral 2608, which may at leastpartially extend along the exterior of the main inflation element 2602.The proximal and distal axially spaced inflation elements 2604, 2606 areexpandable to occlude the renal artery “a” and enclose the reservoir “r”defined between the at least partially inflated main inflation element2602 and the wall of the renal artery “a”. Anesthetic solution “s” ispassed through the apertures 2610 of the main inflation element 2602 fordiffusion through the wall of the renal artery “a” to engulf thetargeted renal nerve tissue. Subsequent to the anesthetic treatment, theproximal and distal axially spaced inflation elements 2604, 2606 may bedeflated and the main inflation element 2602 inflated to position theelectrode 2612 in apposition with the renal artery “a” for treatment ofthe renal nerve tissue “t”.

FIG. 27 illustrates another embodiment of the energy delivery device. Inaccordance with this embodiment, elongate member 2700 includes firstinner balloon or inflation element 2702 mounted adjacent the distal endthereof and second outer balloon or inflation element 2704 coaxiallymounted about the first inner inflation element 2702. The elongatemember 2700 includes a first lumen 2706 in fluid communication with thefirst inner inflation element 2702 through a first port 2708 within thewall of the elongate member 2700. The elongate member 2700 includes asecond lumen 2710 in fluid communication with the second outer inflationelement 2704 through a second port 2712 within the wall of the elongatemember 2700 external of the first inflation element 2702. The secondouter inflation element 2704 includes the helical electrode 2714 fortreatment of tissue and incorporates the apertures 2716 through its wallfor delivery of anesthetic solution. The first inner inflation element2702 is devoid of apertures to define a fully enclosed volume.

In use, the first inflation element 2702 is at least partially inflatedor fully inflated through introduction of irrigation fluids through thefirst lumen 2706 and out the first port 2708. The second inflationelement 2704 is inflated with, e.g., the anesthetic solution “s” throughintroduction of the solution through the second lumen 2710 and thesecond port 2712. The anesthetic solution “s” fills the space orreservoir defined between the inner wall of the second inflation element2704 and the outer wall of the first inflation element 2702. Theanesthetic solution “s” passes through the apertures 2716 for deliverywithin and/or through the wall of the renal artery “a” into the nervestructure “t”. In embodiments, the first inflation element 2702 may befully expanded to the position depicted in FIG. 27 with only a small gapor space defined between the first inflation element 2702 and the secondinflation element 2704. The gap receives the anesthetic solution “s” orthe irrigation fluid. In this condition of the first inflation element2702, the second inflation element 2704 may be pressed against the wallof the renal artery “a” by the first inflation element 2702 therebycausing contact of the helical electrode 2714 with the wall. Inembodiments, a volume of anesthetic solution “s” is disposed between thesmall gap between the first and second inflation elements 2702, 2704 fordispersion through the apertures 2716 as depicted in FIG. 27. In someembodiments, the first inflation element 2702 may be only partiallyexpanded and the second inflation element 2704 is maintained at fullexpansion via the introduction of the anesthetic solution “s” toposition the electrode 2714 adjacent the renal artery during theanesthetic delivery.

Subsequent to the treatment with the anesthetic solution “s”, theirrigation fluid is introduced through the second lumen 2710 and intothe interior volume of the second inflation element 2704. The irrigationfluids pass through the apertures 2716 to cool the electrode 2714 and/orsurrounding tissue. The first inner inflation element 2702 maybeinflated/deflated to any predetermined inflation state duringintroduction of the anesthetic solution “s” or the irrigation fluidwithin the second inflation element 2704. The independent inflation ofthe first inflation element 2702 to maintain apposition of the electrode2714 against the vessel wall allows the flow rate of anesthetic and/orthe irrigation fluid to be independent of maintenance of the appositionof the electrode 2714 against wall. Additionally, full inflation of thefirst inner inflation element 2702 may reduce the volume and/or flowrate of anesthetic solution “s” or irrigation fluid required to bedelivered while maintaining the electrode(s) 2714 in contact with thevessel wall.

While several embodiments of the disclosure have been shown in thedrawings and/or discussed herein, it is not intended that the disclosurebe limited thereto, as it is intended that the disclosure be as broad inscope as the art will allow and that the specification be read likewise.Therefore, the above description should not be construed as limiting,but merely as exemplifications of particular embodiments. Those skilledin the art will envision other modifications within the scope and spiritof the claims appended hereto.

What is claimed is:
 1. An energy delivery system for deliveringelectrical energy to tissue, the energy delivery system comprising: anelongate catheter member defining a longitudinal axis and dimensionedfor passage within a body vessel; and an expandable treatment membermounted to the catheter member, the treatment member including: aninflatable element adapted to transition between an initial conditionand an at least partially expanded condition upon introduction of ananesthetic solution within the inflatable element; an electrode fordelivering electrical energy to at least nerve tissue associated withthe body vessel to cause at least partial denervation thereof; and atleast one aperture dimensioned to permit passage of the anestheticsolution from the inflatable element to contact the body vessel wherebythe solution enters a wall of the body vessel to at least partiallyanesthetize nerve tissue therewithin.
 2. The energy delivery systemaccording to claim 1 wherein the electrode is mounted to at least theinflatable element of the treatment member.
 3. The energy deliverysystem according to claim 2 wherein the electrode is generally helical.4. The energy delivery system accoiding to claim 1 wherein the at leastone aperture is dimensioned to deliver the anesthetic solution at apressure sufficient to facilitate passage of the anesthetic solution atleast within the wall of the body vessel.
 5. The energy delivery systemaccording to claim 4 wherein at least one of the inflatable element andthe electrode includes a plurality of apertures dimensioned to deliverthe anesthetic solution at the pressure sufficient to cause passage ofthe anesthetic solution at least within the wall of the body vessel. 6.The energy delivery system according to claim 4 wherein the aperturesare each dimensioned to deliver the anesthetic solution at a pressureranging from about 1 atm to about 4 atm.
 7. The energy delivery systemaccording to claim 6 wherein the apertures are each dimensioned todeliver the anesthetic solution at a pressure ranging from about 1 atmto about 4 atm and over a flow range of about 1 to about 20 mL/min. 8.The energy delivery system according to claim 7 wherein each aperturedefines a pore size ranging from about 0.5 mil to about 10 mil.
 9. Theenergy delivery system according to claim 6 wherein the catheter memberdefines a fluid lumen for delivering the anesthetic solution to theinflatable element of the treatment member.
 10. The energy deliverysystem according to claim 9 further comprising a source of anestheticsolution in fluid communication with the fluid lumen of the cathetermember and the inflatable element of the treatment member.
 11. Theenergy delivery system according to claim 10 farther comprising a pumpcouplable to the fluid lumen of the catheter member, the pumpdimensioned to deliver the anesthetic solution from the source to thefluid lumen of the catheter member at a pump pressure sufficient toconvey the anesthetic through the fluid lumen and out the apertures atthe pressure to enhance passage of the anesthetic solution at leastwithin the wall of the body vessel.
 12. The energy delivery systemaccording to claim 11 including a sensor in fluid communication with atleast the fluid lumen of the catheter member.
 13. The energy deliverysystem according to claim 12 wherein the sensor is a pressure sensoradapted to sense pressure corresponding to pressure within theinflatable element.
 14. The energy delivery system according to claim 11wherein the sensor is a flow rate sensor adapted to detect flow rateassociated with passage of the anesthetic solution through the fluidlumen.
 15. The energy delivery system according to claim 12 furthercomprising a controller for controlling operation of the pump.
 16. Theenergy delivery system according to claim 15 wherein the controllerincludes logic responsive to a parameter detected by the sensor to varyoperation of the pump.
 17. The energy delivery system according to claim9 further comprising a source of irrigation fluid in fluid communicationwith the inflatable element of the treatment member for passage throughthe apertures.
 18. The energy delivery system according to claim 17further comprising a valve in fluid communication with the source ofanesthetic solution and the source of irrigation fluid, the valve beingactuable between an anesthetic mode to permit the delivery of theanesthetic solution to the fluid lumen of the catheter member and anirrigation mode to permit the delivery of the irrigation fluid to thefluid lumen of the catheter member.
 19. The energy delivery systemaccording to claim 1 wherein the at least one aperture is dimensioned topermit passage of the anesthetic solution at a pressure whereby theanesthetic solution slowly diffuses through the wall of the body vesseland migrates to the nerve tissue associated with the body vessel. 20.The energy delivery system according to claim 19 wherein the inflatableelement of the treatment member is dimensioned to establish a reservoirbetween the inflatable element and the wall of the body vessel when inthe at least partially expanded condition thereof, the reservoir forreceiving the anesthetic solution for diffusion through the wall of thebody vessel.
 21. The energy delivery system according to claim 20wherein the treatment member includes at least one occluding element,the at least one occluding element defining a dimension greater than acorresponding dimension of the inflatable element when the at least oneinflatable clement is in an at least partially expanded conditionthereof, the at least one occluding element dimensioned to at leastpartially occlude the body vessel to at least partially enclose thereservoir.
 22. The energy delivery system according to claim 21 whereinthe inflatable element is a balloon member, the balloon member includingfirst and second axially spaced occluding segments and a central segmentbetween the first and second occluding segments, each of the first andsecond occluding segments having a transverse dimension greater than acorresponding transverse dimension of the central segment when theballoon member is in a first inflated condition, and being dimensionedto substantially occlude the body vessel to enclose the reservoir. 23.The energy delivery system according to claim 22 wherein the balloonmember is adapted to transition between the first inflated condition anda second inflated condition where the central segment defines a greatertransverse dimension to position the electrode in apposition with thebody vessel to deliver electrical energy to the nerve tissue surroundingthe body vessel.
 24. The energy delivery system according to claim 23wherein the catheter member defines a fluid lumen for delivering theanesthetic solution to the balloon member.
 25. The energy deliverysystem according to claim 20 wherein the catheter member includes firstand second occluding elements mounted adjacent opposed ends of theinflation element, the first and second occluding elements adapted toexpand to occlude the body vessel and enclose the reservoir establishedbetween the inflatable element and the wall of the body vessel, thefirst and second occluding elements adapted for expansion independent ofexpansion of the inflatable element.
 26. The energy delivery systemaccording to claim 25 wherein the first and second occluding elementsare first and second occluding balloon members and the inflation elementis a treatment balloon member.
 27. The energy delivery system accordingto claim 26 wherein the catheter member defines a second fluid lumen fordelivering fluid to the first and second occluding balloon members. 28.The energy delivery system according to claim 26 wherein the first andsecond occluding balloon members are inflatable independent of eachother.
 29. The energy delivery system according to claim 19 wherein thetreatment member includes a first balloon member and a second balloonmember coaxially mounted about the first balloon member, the first andsecond balloon members establishing a reservoir between the first andsecond balloon members when in the at least partially inflated conditionthereof, the reservoir for receiving the anesthetic solution, the secondballoon member including the at least one aperture dimensioned to permitpassage of the anesthetic solution and having the electrode mountedthereto.
 30. The energy delivery system according to claim 29 whereinthe first and second balloon members are inflatable independent of eachother.
 31. The energy delivery system according to claim 30 wherein theelongate member defines a second lumen for supplying fluids to the firstballoon member to inflate the first balloon member.
 32. A method fortreating hypertension, comprising: positioning a treatment memberincluding an inflatable segment and an electrode segment within a renalartery; delivering an anesthetic solution into the inflatable segmentsuch that the anesthetic solution is released from at least one apertureof the treatment member to contact a wall of the renal artery wherebythe anesthetic solution at least enters the wall of the renal artery andmigrates to nerve tissue associated with the renal artery; and emittingRF energy from the electrode segment to disrupt renal nerve transmissionto treat hypertension.
 33. The method according to claim 32 whereindelivering the anesthetic solution includes directing the anestheticsolution at a pressure sufficient to enter the wall of the renal arteryand contact the renal nerve tissue.
 34. The method according to claim 33wherein delivering the anesthetic solution includes directing theanesthetic solution through a plurality of apertures in the treatmentmember.
 35. The method according to claim 34 wherein delivering theanesthetic solution includes directing the anesthetic solution through aplurality of apertures in the treatment member at a pressure rangingfrom about 1 atm to about 4 atm.
 36. The method according to claim 32wherein delivering the anesthetic solution includes permitting passageof the anesthetic solution at a pressure whereby the anesthetic solutionslowly diffuses through the wall of the renal artery and migrates to therenal nerve tissue surrounding the renal artery.
 37. The methodaccording to claim 36 wherein delivering the anesthetic solutionincludes distributing the anesthetic solution within a reservoir definedbetween the inflatable segment and the wall of the renal artery.
 38. Themethod according to claim 37 wherein the treatment member includesoccluding segments adjacent each end of the inflation segment andfurther including expanding the occluding segments to contact the wallof the renal artery to occlude the artery and substantially enclose thereservoir.